U.S. patent application number 12/969380 was filed with the patent office on 2011-11-17 for apparatus and method for regulating flow through a pumpbox.
This patent application is currently assigned to SUNCOR ENERGY INC.. Invention is credited to William Nicholas Garner, Thomas Charles Hann.
Application Number | 20110278240 12/969380 |
Document ID | / |
Family ID | 44189451 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110278240 |
Kind Code |
A1 |
Hann; Thomas Charles ; et
al. |
November 17, 2011 |
APPARATUS AND METHOD FOR REGULATING FLOW THROUGH A PUMPBOX
Abstract
A pumpbox apparatus includes a reservoir volume having a first
inlet for receiving a feedstock stream and a second inlet for
receiving a water stream, the reservoir volume being in
communication with a discharge outlet disposed to discharge
accumulated liquid from the reservoir volume. The reservoir volume
is operable to accumulate the feedstock stream and the water stream
in the reservoir volume while withdrawing a discharge stream
through the discharge outlet to cause a flow of liquid through the
pumpbox. The first inlet defines a first flow velocity region
between the first inlet and the second inlet and a second flow
velocity region between the second inlet and the discharge outlet.
The first flow velocity is lower than the second flow velocity to
facilitate flotation of a low specific gravity portion of the
feedstock through the first region toward an upper surface of the
liquid accumulated in the reservoir volume.
Inventors: |
Hann; Thomas Charles;
(Onoway, CA) ; Garner; William Nicholas; (Fort
McMurray, CA) |
Assignee: |
SUNCOR ENERGY INC.
Calgary
CA
|
Family ID: |
44189451 |
Appl. No.: |
12/969380 |
Filed: |
December 15, 2010 |
Current U.S.
Class: |
210/803 |
Current CPC
Class: |
B03D 1/028 20130101;
B03D 1/1456 20130101; B03D 1/1493 20130101; B03D 1/1468 20130101;
B03D 2203/006 20130101; B03D 1/247 20130101 |
Class at
Publication: |
210/803 |
International
Class: |
B01D 21/00 20060101
B01D021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2009 |
CA |
2689021 |
Claims
1. A pumpbox apparatus for processing a feedstock stream comprising
an aerated bitumen froth, the apparatus comprising: a reservoir
volume having a first inlet for receiving the feedstock stream and
a second inlet for receiving a water stream, the reservoir volume
being in communication with a discharge outlet disposed to
discharge accumulated liquid from the reservoir volume, the
reservoir volume being operable to accumulate the feedstock stream
and the water stream to a first liquid level in the reservoir
volume while withdrawing a discharge stream through the discharge
outlet to cause a flow of liquid through the pumpbox, the first
inlet being located above the second inlet and defining a first
flow velocity region between the first inlet and the second inlet
and a second flow velocity region between the second inlet and the
discharge outlet, the first flow velocity being lower than the
second flow velocity to facilitate flotation of a low specific
gravity portion of the feedstock through the first region toward an
upper surface of the liquid accumulated in the reservoir volume;
and a collector for collecting at least a portion of the low
specific gravity portion from an upper surface of the accumulated
volume when the first liquid level is above the first inlet.
2. The apparatus of claim 1 further comprising a controller for
controlling a flow rate through the discharge outlet to maintain
the first liquid level at a level between the first inlet and a
high liquid level, the high liquid level being a desired maximum
operating level for the reservoir volume.
3. The apparatus of claim 2 wherein the collector is operably
configured to collect at least a portion of the low specific
gravity portion from an upper surface of the accumulated volume
when the first liquid level reaches a high liquid level.
4. The apparatus of claim 2 wherein the collector comprises a
launder having an inlet disposed in the reservoir volume at the
high liquid level for receiving an overflow of the low specific
gravity portion from the reservoir volume.
5. The apparatus of claim 2 wherein the reservoir volume is
selected to maintain a retention time of feedstock and water in the
pumpbox of about 1 minute at an expected average flow rate of the
feedstock stream and the water stream.
6. The apparatus of claim 1 further comprising a discharge pump in
communication with the discharge outlet for withdrawing the
discharge stream from the discharge outlet.
7. The apparatus of claim 6 wherein the discharge pump is operably
configured to discontinue operation when the liquid level reaches a
low liquid level.
8. The apparatus of claim 6 further comprising a controller
operably configured to control operation of the discharge pump in
response to receiving a liquid level signal representing an
accumulation level of liquid in the reservoir volume.
9. The apparatus of claim 1 the feedstock stream comprises a highly
aerated bitumen froth having a density in the range of about 600
kg/m3 to about 1000 kg/m3.
10. The apparatus of claim 9 wherein the feedstock stream comprises
water and solids.
11. The apparatus of claim 1 wherein the water stream comprises a
re-circulated water stream.
12. The apparatus of claim 11 wherein the re-circulated water
stream comprises residual bitumen and solids.
13. The apparatus of claim 1 wherein said second inlet is disposed
to cause solids that settle out of the accumulated liquid volume to
be dispersed toward the discharge outlet for discharge in the
discharge stream.
14. The apparatus of claim 13 wherein said second inlet is oriented
to direct the water stream received at the second inlet generally
towards the discharge outlet.
15. The apparatus of claim 13 wherein the pumpbox comprises a base
having portion that is inclined to direct solids that settle out of
the accumulated liquid volume toward the discharge outlet for
discharge in the discharge stream.
16. The apparatus of claim 1 wherein a density of the discharge
stream is between about 122.times.10.sup.1 and about
128.times.10.sup.1 kg/m.sup.3.
17. The apparatus of claim 1 wherein the flow velocity in the first
flow velocity region is less than about 5.times.10.sup.-2 meters
per second.
18. A pumpbox apparatus for processing a feedstock stream
comprising an aerated bitumen froth, the apparatus comprising: a
reservoir volume having a first inlet for receiving the feedstock
stream and a second inlet for receiving a water stream, the
reservoir volume being in communication with a discharge outlet
disposed to discharge accumulated liquid from the reservoir volume,
the reservoir volume being operable to accumulate the feedstock
stream and the water stream to a first liquid level in the
reservoir volume while withdrawing a discharge stream through the
discharge outlet to cause a flow of liquid through the pumpbox, the
first inlet being located above the second inlet and defining a
first flow velocity region between the first inlet and the second
inlet and a second flow velocity region between the second inlet
and the discharge outlet, the first flow velocity being lower than
the second flow velocity to facilitate flotation of a low specific
gravity portion of the feedstock through the first region toward an
upper surface of the liquid accumulated in the reservoir volume;
and means for collecting at least a portion of the low specific
gravity portion from an upper surface of the accumulated volume
when the first liquid level is above the first inlet.
19. The apparatus of claim 18 further comprising means for
controlling a flow rate through the discharge outlet to maintain
the first liquid level at a level between the first inlet and a
high liquid level, the high liquid level being a desired maximum
operating level for the pumpbox.
20. The apparatus of claim 19 wherein said means for collecting
comprises means for collecting at least a portion of the low
specific gravity portion from an upper surface of the accumulated
volume when the first liquid level reaches a high liquid level.
21. The apparatus of claim 19 wherein said means for controlling
comprises means for controlling a flow rate through the discharge
outlet to maintain a retention time of the feedstock stream and
water stream in the reservoir volume of about 1 minute.
22. The apparatus of claim 18 wherein the feedstock stream
comprises a highly aerated bitumen froth.
23. The apparatus of claim 22 wherein the feedstock stream further
comprises water and solids.
24. The apparatus of claim 18 wherein the water stream comprises a
re-circulated water stream.
25. The apparatus of claim 24 wherein the re-circulated water
stream comprises at least one of residual bitumen and solids.
26. The apparatus of claim 18 further comprising means for causing
solids that settle out of the accumulated liquid volume to be
dispersed toward the discharge outlet for discharge in the
discharge stream.
27. The apparatus of claim 18 wherein a density of the discharge
stream is between about 122.times.10.sup.1 and about
128.times.10.sup.1 kg/m.sup.3.
28. The apparatus of claim 18 wherein the flow velocity in the
first flow velocity region is less than about 5.times.10.sup.-2
meters per second.
29. A method for regulating flow through a pumpbox having a
reservoir volume in communication with a discharge outlet disposed
to discharge accumulated liquid from the reservoir volume, the
method comprising: receiving a feedstock stream at a first inlet of
the reservoir volume, the feedstock comprising an aerated bitumen
froth; receiving a water stream at a second inlet of the reservoir
volume; accumulating the feedstock stream and the water stream to a
first liquid level in the reservoir volume while withdrawing a
discharge stream through the discharge outlet to cause a flow of
liquid through the pumpbox, the first inlet being located above the
second inlet and defining a first flow velocity region between the
first inlet and the second inlet and a second flow velocity region
between the second inlet and the discharge outlet, the first flow
velocity being lower than the second flow velocity to facilitate
flotation of a low specific gravity portion of the feedstock
through the first region toward an upper surface of the liquid
accumulated in the reservoir volume; and collecting at least a
portion of the low specific gravity portion from an upper surface
of the accumulated volume when the first liquid level is above the
first inlet.
30. The method of claim 29 further comprising controlling a flow
rate through the discharge outlet to maintain the first liquid
level at a level between the first inlet and a high liquid level,
the high liquid level being a desired maximum operating level for
the reservoir volume.
31. The method of claim 30 wherein collecting comprises collecting
at least a portion of the low specific gravity portion from an
upper surface of the accumulated volume when the first liquid level
reaches a high liquid level.
32. The method of claim 30 wherein collecting comprises causing the
low specific gravity portion to overflow into a launder having an
inlet disposed in the reservoir volume at the high liquid
level.
33. The method of claim 29 wherein withdrawing the discharge stream
comprises operating a discharge pump in communication with the
discharge outlet.
34. The method of claim 33 further comprising discontinuing
operation of the discharge pump when the liquid level reaches a low
liquid level.
35. The method of claim 33 further comprising controlling operation
of the discharge pump in response to receiving a liquid level
signal representing an accumulation level of liquid in the
reservoir volume.
36. The method of claim 29 wherein receiving the feedstock stream
comprises receiving a feedstock stream comprising a highly aerated
bitumen froth.
37. The method of claim 36 wherein receiving the feedstock stream
comprises receiving a feedstock stream comprising water and
solids.
38. The method of claim 29 wherein receiving the water stream
comprises receiving a re-circulated water stream.
39. The method of claim 38 wherein receiving the re-circulated
water stream comprises receiving a re-circulated water stream
comprising residual bitumen and solids.
40. The method of claim 29 further comprising causing solids that
settle out of the accumulated liquid volume to be dispersed toward
the discharge outlet for discharge in the discharge stream.
41. The method of claim 40 wherein causing solids that settle out
of the accumulated liquid volume to be dispersed comprises
directing the water stream received at the second inlet generally
towards the discharge outlet.
42. The method of claim 29 wherein a density of the discharge
stream is between about 122.times.10.sup.1 and about
128.times.10.sup.1 kg/m.sup.3.
43. The method of claim 29 wherein the flow velocity in the first
flow velocity region is less than about 5.times.10.sup.-2 meters
per second.
44. A system for extracting bitumen from a feedstock, the system
comprising: a pumpbox comprising a reservoir volume having a first
inlet for receiving a feedstock stream comprising a bitumen froth
and a second inlet for receiving a water stream, the reservoir
volume being in communication with a discharge outlet disposed to
discharge accumulated liquid from the reservoir volume, the
reservoir volume being operable to accumulate the feedstock stream
and the water stream to a first liquid level in the reservoir
volume while withdrawing a discharge stream through the discharge
outlet to cause a flow of liquid through the pumpbox, the first
inlet being located above the second inlet and defining a first
flow velocity region between the first inlet and the second inlet
and a second flow velocity region between the second inlet and the
discharge outlet, the first flow velocity being lower than the
second flow velocity to facilitate flotation of at least a portion
of the bitumen froth through the first region toward an upper
surface of the liquid accumulated in the reservoir volume; a first
hydrocyclone having a feed inlet, an overflow outlet for producing
a first product stream, and an underflow outlet, the feed inlet of
the first hydrocyclone being in communication with the discharge
outlet of the pumpbox for receiving the discharge stream from the
pumpbox; a second hydrocyclone having a feed inlet, an overflow
outlet, and an underflow outlet for producing a first tailings
stream, the feed inlet of the second hydrocyclone being in
communication with the underflow outlet of the first hydrocyclone,
the overflow outlet of the second hydrocyclone being in
communication with the second inlet of the pumpbox for providing
the water stream to the pumpbox; and wherein the pumpbox further
comprises a collector for collecting at least a portion of the low
specific gravity bitumen portion from an upper surface of the
accumulated volume when the first liquid level is above the first
inlet to produce a second product stream, the second product stream
being combined with the first product stream to produce a system
product stream.
45. The system of claim 44 further comprising a third hydrocyclone
having a feed inlet, an overflow outlet, and an underflow outlet,
the feed inlet of the third hydrocyclone being in communication
with the underflow outlet of the second hydrocyclone for receiving
the first tailings stream, the third hydrocyclone being operable to
produce a second tailings stream at the underflow outlet of the
second hydrocyclone, the overflow outlet of the third hydrocyclone
being in communication with the feed inlet of the second
hydrocyclone to provide an additional feed to the second
hydrocyclone.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] This invention relates generally to processing of a
feedstock and more particularly to a pumpbox for receiving a
hydrocarbon feedstock.
[0003] 2. Description of Related Art
[0004] Hydrocarbon feedstocks are generally viscous and may be
entrained with other components such as rock, sand, clay and other
minerals. As a result, such feedstocks require processing to
separate useful hydrocarbon products from residue before transport
and refining.
[0005] One example of a hydrocarbon ore deposit is the Northern
Alberta oil sands, which comprises about 70 to about 90 percent by
weight of mineral solids including sand and clay, about 1 to about
10 percent by weight of water, and a bitumen or oil film. The
bitumen may be present in amounts ranging from a trace amount up to
as much as 20 percent by weight. Due to the highly viscous nature
of bitumen, when excavated some of the ore may remain as clumps of
oversize ore that requires sizing to produce a sized ore feed
suitable for processing. The ore may also be frozen due to the
northerly geographic location of many oil sands deposits, making
sizing of the ore more difficult. The sized ore feed is typically
processed by adding water to form a slurry in a location proximate
to the ore deposit, and the resulting slurry is hydro-transported
through a pipeline to a processing plant, where the slurry forms
the feedstock for a processing plant that separates hydrocarbon
products from the sand and other minerals.
[0006] Low specific gravity hydrocarbons such as bitumen froth may
be separated from sand and water, which generally have higher
specific gravity, by various gravity separation processes. There
remains a need for improved processes and apparatus for treating
heavy hydrocarbon feedstocks.
SUMMARY OF THE INVENTION
[0007] In accordance with one aspect of the invention there is
provided a pumpbox apparatus. The apparatus includes a reservoir
volume having a first inlet for receiving a feedstock stream and a
second inlet for receiving a water stream, the reservoir volume
being in communication with a discharge outlet disposed to
discharge accumulated liquid from the reservoir volume. The
reservoir volume is operable to accumulate the feedstock stream and
the water stream to a first liquid level in the reservoir volume
while withdrawing a discharge stream through the discharge outlet
to cause a flow of liquid through the pumpbox. The first inlet is
located above the second inlet and defines a first flow velocity
region between the first inlet and the second inlet and a second
flow velocity region between the second inlet and the discharge
outlet. The first flow velocity is lower than the second flow
velocity to facilitate flotation of a low specific gravity portion
of the feedstock through the first region toward an upper surface
of the liquid accumulated in the reservoir volume. The apparatus
also includes a collector for collecting at least a portion of the
low specific gravity portion from an upper surface of the
accumulated volume when the first liquid level is above the first
inlet.
[0008] The apparatus may include a controller for controlling a
flow rate through the discharge outlet to maintain the first liquid
level at a level between the first inlet and a high liquid level,
the high liquid level being a desired maximum operating level for
the reservoir volume.
[0009] The collector may be operably configured to collect at least
a portion of the low specific gravity portion from an upper surface
of the accumulated volume when the first liquid level reaches a
high liquid level.
[0010] The collector may include a launder having an inlet disposed
in the reservoir volume at the high liquid level for receiving an
overflow of the low specific gravity portion from the reservoir
volume.
[0011] The reservoir volume may be selected to maintain a retention
time of feedstock and water in the pumpbox in the range of about 30
seconds to about several minutes at an expected average flow rate
of the feedstock stream and the water stream. In one arrangement,
the retention time is about 1 minute.
[0012] The apparatus may include a discharge pump in communication
with the discharge outlet for withdrawing the discharge stream from
the discharge outlet.
[0013] The discharge pump may be operably configured to discontinue
operation when the liquid level reaches a low liquid level.
[0014] The apparatus may include a controller operably configured
to control operation of the discharge pump in response to receiving
a liquid level signal representing an accumulation level of liquid
in the reservoir volume.
[0015] The feedstock stream may include bitumen. In one embodiment,
the feedstock stream comprises bitumen froth. In another
embodiment, the bitumen froth is in the form of an aerated froth.
In another variation, the feedstock stream comprises bitumen froth
in the form of a highly aerated bitumen froth. Highly aerated
bitumen froths tend to float fast. Advantageously, in one aspect of
the invention, the vessel is operative to selectively separate out
such a fast floating aerated bitumen froth.
[0016] The feedstock stream may include water and solids.
[0017] The water stream may include a re-circulated water
stream.
[0018] The re-circulated water stream may include residual bitumen
and solids.
[0019] The second inlet may be disposed to cause solids that settle
out of the accumulated liquid volume to be dispersed toward the
discharge outlet for discharge in the discharge stream.
[0020] The second inlet may be oriented to direct the water stream
received at the second inlet generally towards the discharge
outlet.
[0021] The pumpbox may include a base having portion that may be
inclined to direct solids that settle out of the accumulated liquid
volume toward the discharge outlet for discharge in the discharge
stream.
[0022] A density of the discharge stream may be between about
122.times.10.sup.1 and about 128.times.10.sup.1 kg/m3.
[0023] The flow velocity in the first flow velocity region may be
less than about 5.times.10.sup.-2 meters per second.
[0024] In accordance with another aspect of the invention there is
provided a pumpbox apparatus. The apparatus includes a reservoir
volume having a first inlet for receiving a feedstock stream and a
second inlet for receiving a water stream, the reservoir volume
being in communication with a discharge outlet disposed to
discharge accumulated liquid from the reservoir volume. The
reservoir volume is operable to accumulate the feedstock stream and
the water stream to a first liquid level in the reservoir volume
while withdrawing a discharge stream through the discharge outlet
to cause a flow of liquid through the pumpbox. The first inlet is
located above the second inlet and defines a first flow velocity
region between the first inlet and the second inlet and a second
flow velocity region between the second inlet and the discharge
outlet, the first flow velocity being lower than the second flow
velocity to facilitate flotation of a low specific gravity portion
of the feedstock through the first region toward an upper surface
of the liquid accumulated in the reservoir volume. The apparatus
also includes provisions for collecting at least a portion of the
low specific gravity portion from an upper surface of the
accumulated volume when the first liquid level is above the first
inlet.
[0025] The apparatus may include provisions for controlling a flow
rate through the discharge outlet to maintain the first liquid
level at a level between the first inlet and a high liquid level,
the high liquid level being a desired maximum operating level for
the pumpbox.
[0026] The provisions for collecting may include provisions for
collecting at least a portion of the low specific gravity portion
from an upper surface of the accumulated volume when the first
liquid level reaches a high liquid level.
[0027] The provisions for controlling may include provisions for
controlling a flow rate through the discharge outlet to maintain a
retention time of the feedstock stream and water stream in the
reservoir volume of about 1 minute.
[0028] The apparatus may include provisions for causing solids that
settle out of the accumulated liquid volume to be dispersed toward
the discharge outlet for discharge in the discharge stream.
[0029] A density of the discharge stream may be between about
122.times.10.sup.1 and about 128.times.10.sup.1 kg/m3.
[0030] The flow velocity in the first flow velocity region may be
less than about 5.times.10.sup.-2 meters per second.
[0031] In accordance with another aspect of the invention there is
provided a method for regulating flow through a pumpbox having a
reservoir volume in communication with a discharge outlet disposed
to discharge accumulated liquid from the reservoir volume. The
method involves receiving a feedstock stream at a first inlet of
the reservoir volume, receiving a water stream at a second inlet of
the reservoir volume, and accumulating the feedstock stream and the
water stream to a first liquid level in the reservoir volume while
withdrawing a discharge stream through the discharge outlet to
cause a flow of liquid through the pumpbox. The first inlet is
located above the second inlet and defines a first flow velocity
region between the first inlet and the second inlet and a second
flow velocity region between the second inlet and the discharge
outlet, the first flow velocity being lower than the second flow
velocity to facilitate flotation of a low specific gravity portion
of the feedstock through the first region toward an upper surface
of the liquid accumulated in the reservoir volume. The method
further involves collecting at least a portion of the low specific
gravity portion from an upper surface of the accumulated volume
when the first liquid level is above the first inlet.
[0032] The method may involve controlling a flow rate through the
discharge outlet to maintain the first liquid level at a level
between the first inlet and a high liquid level, the high liquid
level being a desired maximum operating level for the reservoir
volume.
[0033] Collecting may involve collecting at least a portion of the
low specific gravity portion from an upper surface of the
accumulated volume when the first liquid level reaches a high
liquid level.
[0034] Collecting may involve causing the low specific gravity
portion to overflow into a launder having an inlet disposed in the
reservoir volume at the high liquid level.
[0035] Withdrawing the discharge stream may involve operating a
discharge pump in communication with the discharge outlet.
[0036] The method may involve discontinuing operation of the
discharge pump when the liquid level reaches a low liquid
level.
[0037] The method may involve controlling operation of the
discharge pump in response to receiving a liquid level signal
representing an accumulation level of liquid in the reservoir
volume.
[0038] The method may involve causing solids that settle out of the
accumulated liquid volume to be dispersed toward the discharge
outlet for discharge in the discharge stream.
[0039] Causing solids that settle out of the accumulated liquid
volume to be dispersed may involve directing the water stream
received at the second inlet generally towards the discharge
outlet.
[0040] A density of the discharge stream may be between about
122.times.10.sup.1 and about 128.times.10.sup.1 kg/m3.
[0041] The flow velocity in the first flow velocity region may be
less than about 5.times.10.sup.-2 meters per second.
[0042] In accordance with one aspect of the invention there is
provided a system for extracting bitumen from a feedstock. The
system includes a pumpbox including a reservoir volume having a
first inlet for receiving a feedstock stream including bitumen and
a second inlet for receiving a water stream. The reservoir volume
is in communication with a discharge outlet disposed to discharge
accumulated liquid from the reservoir volume. The reservoir volume
is operable to accumulate the feedstock stream and the water stream
to a first liquid level in the reservoir volume while withdrawing a
discharge stream through the discharge outlet to cause a flow of
liquid through the pumpbox. The first inlet is located above the
second inlet and defines a first flow velocity region between the
first inlet and the second inlet and a second flow velocity region
between the second inlet and the discharge outlet. The first flow
velocity is lower than the second flow velocity to facilitate
flotation of at least a portion of the bitumen through the first
region toward an upper surface of the liquid accumulated in the
reservoir volume. The system also includes a first hydrocyclone
having a feed inlet, an overflow discharge outlet for producing a
first product stream, and an underflow discharge outlet, the feed
inlet of the first hydrocyclone being in communication with the
discharge outlet of the pumpbox for receiving the discharge stream
from the pumpbox. The system further includes a second hydrocyclone
having a feed inlet, an overflow discharge outlet, and an underflow
discharge outlet for producing a first tailings stream, the feed
inlet of the second hydrocyclone being in communication with the
underflow discharge outlet of the first hydrocyclone. The overflow
discharge outlet of the second hydrocyclone is in communication
with the second inlet of the pumpbox for providing the water stream
to the pumpbox. The pumpbox further includes a collector for
collecting at least a portion of the low specific gravity bitumen
portion from an upper surface of the accumulated volume when the
first liquid level is above the first inlet to produce a second
product stream, the second product stream being combined with the
first product stream to produce a system product stream.
[0043] The system may include a third hydrocyclone having a feed
inlet, an overflow discharge outlet, and an underflow discharge
outlet, the feed inlet of the third hydrocyclone being in
communication with the underflow discharge outlet of the second
hydrocyclone for receiving the first tailings stream, the third
hydrocyclone being operable to produce a second tailings stream at
the underflow discharge outlet of the second hydrocyclone, the
overflow discharge outlet of the third hydrocyclone being in
communication with the feed inlet of the second hydrocyclone to
provide an additional feed to the second hydrocyclone.
[0044] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of the
invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In drawings which illustrate embodiments of the
invention,
[0046] FIG. 1 is a perspective partially cut-away view of a pumpbox
apparatus in accordance with a first embodiment of the
invention;
[0047] FIG. 2 is a side schematic view of the pumpbox shown in FIG.
2; and
[0048] FIG. 3 is a schematic flow diagram of a system for
extracting bitumen employing the pumpbox shown in FIG. 1.
DETAILED DESCRIPTION
[0049] Referring to FIG. 1, a pumpbox apparatus according to a
first embodiment of the invention is shown generally at 100. The
pumpbox apparatus 100 includes a reservoir volume 102 having a
first inlet 104 for receiving a feedstock stream and a second inlet
106 for receiving a water stream. The reservoir volume 102 is in
communication with a discharge outlet 108 disposed to discharge
accumulated liquid from the reservoir volume. The reservoir volume
102 is operable to accumulate the feedstock stream received at the
first inlet 104 and the water stream received at the second inlet
106 to a first liquid level in the reservoir volume while
withdrawing a discharge stream through the discharge outlet 108 to
cause a flow of liquid through the pumpbox apparatus 100. In one
embodiment the density of the discharge stream may be between about
122.times.10.sup.1 and about 128.times.10.sup.1 kg/m3.
[0050] The first inlet 104 is located above the second inlet 106.
In this embodiment the first inlet 104 is in communication with a
feed conduit 105, which is receives the feedstock stream, and
directs the stream to the first inlet 104. The pumpbox apparatus
100 is shown in side schematic view in FIG. 2. Referring to FIG. 2,
the feedstock stream received at the first inlet 104 and the water
stream received at the second inlet 106 cause respective flows 142
and 144 in the reservoir volume 102. A first flow velocity region
144 is defined between the first inlet 104 and the second inlet
106. A second flow velocity region 146 is defined generally between
the second inlet 106 and the discharge outlet 108. A first flow
velocity in the first region 144 is lower than a second flow
velocity in the second region 144, which facilitates flotation of a
low specific gravity portion of the feedstock through the first
region 144 toward an upper surface 148 of the liquid accumulated in
the reservoir volume 102.
[0051] The flow through the first and second flow velocity regions
144 and 146 is generally in a downwards direction and in one
embodiment where the feedstock stream comprises bitumen, the first
flow velocity is less than about 5.times.10.sup.-2 meters per
second, which permits a fast rising bitumen portion to float
upwardly in the reservoir volume 102. Referring back to FIG. 1, the
pumpbox apparatus 100 further includes a collector 110 for
collecting at least a portion of the low specific gravity portion
of the feedstock from the upper surface 148 when the first liquid
level is above the first inlet 104.
[0052] In the embodiment shown in FIG. 2, the pumpbox apparatus 100
further includes a discharge pump 160. The discharge pump 160
includes an inlet 162 in communication with the discharge outlet
108 for withdrawing the discharge stream from the pumpbox. The pump
160 also has an outlet 164, which may be coupled to a conduit for
conveying the discharged stream for further processing. The pump
160 also includes the control input 166 for receiving a pump
control signal for controlling operation of the pump.
[0053] In the embodiment shown in FIG. 1 and FIG. 2 the collector
110 is configured as a launder having an overflow inlet 112 and a
product outlet 114 for producing a product stream. When the first
liquid level in the reservoir volume 102 reaches the level of the
inlet 112 the lower specific gravity portion which accumulates at
the upper surface 148 overflows into the launder and is discharged
through the product outlet 114. Referring back to FIG. 2, the
overflow inlet 112 thus defines a high liquid level (HLL) for the
reservoir volume 102.
[0054] In this embodiment, the apparatus 100 also includes a liquid
level sensor 170 and an opening 172 in a sidewall 174 of the
pumpbox, which permits sensing of the first liquid level in the
reservoir volume 102. The level sensor 170 includes an output 176
for producing a level signal representing a liquid level in the
reservoir volume 102. The apparatus 100 further includes a
controller 180 having an input 182 for receiving the level signal
from the output 176 of the level sensor 170. The controller 180
also includes an output 184 for producing the pump control signal
for controlling operation of the pump 160. In one embodiment, the
control signal received at the input 166 of the pump 160 may be an
analog signal that controls a speed of the pump, and thus the
discharge flow rate through the discharge outlet 108. In other
embodiments, the control signal may be a signal having one of two
states, including a first state for causing the pump 160 to
operate, and a second state for causing the pump to discontinue
operation.
[0055] Referring back to FIG. 1, in the illustrative embodiment the
pumpbox apparatus includes a plurality of sidewalls 120 supported
by a frame 122, a base 124, and a back plate 126, which together
define the reservoir volume 102. The back plate 126 is inclined at
an angle to the base 124 to cause solids that settle out from the
accumulated liquid to be generally directed toward the discharge
outlet 108. The apparatus 100 may also include a drain outlet 128
located below the discharge outlet 108. The drain outlet
facilitates periodic or selective flushing of the pumpbox for
inspection of the apparatus. Note that while the pumpbox apparatus
may have a rectangular outline, curved surfaces may be used in
connection with the apparatus in another variation to provide
further structural strength.
[0056] The feedstock stream received at the first inlet 104 may be
an oil sand slurry including mineral solids such as sand and clay,
water, and a bitumen froth. Preferably, the feedstock stream
includes a highly aerated bitumen froth. Highly aerated bitumen
froth tends to float fast. Advantageously, in one aspect of the
invention, the pumpbox apparatus is operative to selectively
separate out such a fast floating aerated bitumen froth.
[0057] In one embodiment the upstream oil sand flow rate of an oil
sand feed may be in the range of about 1000 and about 6000 tonnes
per hour. The oil sand feed is diluted with water (e.g. process
water) to produce a slurry having densities in the range of about
1400 kg/m3 to about 1650 kg/m3, which is received at the first
inlet 104. The water stream received at the second inlet 106 may be
re-circulated process water, which may include dispersed solids and
at least some residual bitumen.
[0058] During operation of the pumpbox apparatus 100, the feedstock
stream and the water stream accumulate in the reservoir volume 102
while the controller 180 monitors the liquid level signal produced
by the level sensor 170. When the first liquid level reaches the
low liquid level (indicated as LLL in FIG. 2), the controller 180
responds by changing the state of the pump control signal produced
at the output 184, which in turn causes the discharge pump 160 to
be activated to cause accumulated liquid in the reservoir volume
102 to be discharged through the discharge outlet 108. As the first
liquid level in the reservoir volume 102 continues to rise, the
controller 180 may respond by increasing the speed of the discharge
pump 160 to increase the discharge flow rate through the discharge
outlet 108. When the first liquid level reaches the level of the
first inlet 104, the first and second flow velocity regions 144 and
146 are established. Volumetric flow rates through the pumpbox
apparatus 100 may be written as follows:
Q.sub.D=Q.sub.1+Q.sub.2 Eqn 1
where Q.sub.D is the volumetric flow rate through the discharge
outlet 108, Q.sub.1 is the volumetric flow rate in the first region
144, and Q.sub.2 is the volumetric flow rate through the second
region 146. Assuming a downwardly vertical flow, the volumetric
flow rate in the first region 144 may be written as:
Q.sub.1=Av.sub.1 Eqn 2
where A is the cross-sectional area of the reservoir volume 102,
v.sub.1 is the flow velocity in the first region 144. Rearranging
and substituting Eqn 2 into Eqn 1 gives:
Q.sub.2=Q.sub.D-AV.sub.1 Eqn 3
[0059] For example, at a discharge rate of 2000 m.sup.3/hour
through the discharge outlet 108 in a vessel having a
cross-sectional area of 8 m.sup.2, in order to maintain a velocity
v.sub.1 of 5.times.10.sup.-2 meters per second, the flow rate
through the second inlet 106 should be about 560 m.sup.3/hour.
Under these conditions a velocity v.sub.2 in the second region 146
would be about 7.times.10.sup.-2 meters per second. Advantageously,
the reduced first flow velocity v.sub.1 in the first region 144
facilitates flotation of the low specific gravity portion of the
feedstock through the first region 144 to the upper surface 148.
Equations 1-3 above are derived under assumption of vertically
downward flow. In practice, flow paths through the apparatus 100
will have portions that are not vertically downward. It should thus
be appreciated that for accurate calculation the above analysis
would need to be applied to actual flow paths through the
apparatus.
[0060] In the embodiment shown, collection of the low specific
gravity portion of the feedstock that floats to the upper surface
148 occurs when the first liquid level in the reservoir volume 102
reaches the level of the overflow inlet 112 of the collector 110.
The overflow inlet 112 therefore defines a high liquid level (HLL)
for operation of the pumpbox apparatus 100. Generally, while it may
be desirable to always operate the pumpbox apparatus 100 at the HLL
in order to facilitate continuous collection of the low specific
gravity portion of the feedstock, in practice variations in flow
rate of the feedstock stream through the first inlet 104 would
necessarily result in deviations from HLL that would require
periodic intervention by an operator to adjust the discharge flow
rate Q.sub.D and/or the flow rate Q.sub.2 of the water stream.
Practically, the operator would seek to maintain the first liquid
level in the reservoir volume 102 between a normal liquid level
(NLL) located at or above the first inlet 104 and the HLL. The NLL
assumes liquid densities are about a nominal fluid density. Aerated
bitumen froth, due to the air content, has a lower density hence a
higher level than the nominal fluid. Aerated bitumen froth may have
a density ranging from about 600 kg/m3 to about 1000 kg/m3.
[0061] While the first liquid level is maintained between NLL and
HLL and the velocity v.sub.1 is maintained below less than about
5.times.10.sup.-2 meters per second, favorable conditions for
flotation of the low specific gravity portion of the feedstock
exists and bitumen should accumulate at the upper surface. When the
first liquid level is above NLL but below HLL, bitumen may
accumulate, but would not be collected. Accumulated bitumen is
collected when the various flows permit the first liquid level in
the reservoir volume to rise to the HLL. In one embodiment the
discharge pump 160 is operated to maintain the first liquid level
at an average liquid level of about 75% of the vertical distance
between NLL and HLL above the NLL.
[0062] Referring to FIG. 3, a flow diagram of a system for
extracting bitumen from a slurry of bitumen, solids, and water
according to one embodiment of the invention is shown generally at
200. The system 200 includes a plurality of generally conically
shaped hydrocyclones, including a first hydrocyclone 202, a second
hydrocyclone 204, and a third hydrocyclone 206. The first
hydrocyclone 202 includes a feed inlet 210, an overflow outlet 212,
and an underflow outlet 214. The second hydrocyclone 204 includes a
feed inlet 216, an overflow outlet 218, and an underflow outlet
220. The third hydrocyclone 206 includes a feed inlet 222, an
overflow outlet 224, and an underflow outlet 226.
[0063] In general, hydrocyclones operate by receiving a
tangentially oriented flow at the feed inlet and a resulting
circumferential flow transports heavier solid particles outwardly
towards the walls of the hydrocyclone allowing lower specific
gravity components and a portion of the water to be extracted as an
overflow stream at the overflow outlet. The solids and a remaining
portion of the water exit the hydrocyclone at the underflow outlet.
Suitable hydrocyclones for the cyclone separation stages include
those manufactured by FLSmidth Krebs of Tucson Ariz., USA under the
trademark gMAX.RTM.. Alternatively, Cavex hydrocyclones marketed by
Warman International may be used.
[0064] The system 200 further includes the pumpbox apparatus 100
shown in FIG. 1 and FIG. 2. The feedstock received at the first
inlet 104 of the pumpbox apparatus 100 includes solids and/or
minerals in a significant portion, by weight. For example, the
feedstock may have a composition of about 5 wt % to about 15 wt %
bitumen, about 40 wt % to about 70 wt % solids (including
minerals), and about 30 wt % to about 75 wt % water. The pumpbox
apparatus 100 generally operates as described above, and a portion
of the low specific gravity bitumen in the feedstock that readily
floats to the upper surface 148 of the accumulated liquid in the
reservoir volume 102 overflows through the product outlet 114, and
forms a first product stream 228. The remaining water, solids, and
a portion of the bitumen is discharged through the discharge outlet
108 of the pumpbox apparatus 100 and forms the feed stream at the
feed inlet 210 of the first hydrocyclone 202.
[0065] The first hydrocyclone 202 separates the feed received at
the inlet 210 and produces a second product stream 230 of low
specific gravity bitumen, water, and some fine entrained solids at
the overflow outlet 212 and an underflow stream including solids,
water, and a bitumen portion at the underflow outlet 214. The
second product stream 230 is mixed with the first product stream
228 to produce a combined product stream 232 from the system 200,
which may be further processed to separate the low specific gravity
bitumen components from the water. In general mixing of the second
product stream 230 and the first product stream 228 would occur in
a conventional pumpbox.
[0066] The underflow at the outlet 214 is fed to the feed inlet 216
of the second hydrocyclone 204. The second hydrocyclone 204 further
separates the feed into a low specific gravity overflow stream
including mostly water, some bitumen, and some fine solids. The
overflow outlet 218 of the second hydrocyclone 204 is fed to the
second inlet 106 of the pumpbox apparatus 100, and forms the water
stream inlet for the pumpbox. The underflow stream produced by the
second hydrocyclone 204 at the outlet 220 and a system process
water feed 208 are combined to make up the feed to the inlet 222 of
the third hydrocyclone 206. The combining of these streams may
occur in a conventional pumpbox, for example.
[0067] The third hydrocyclone 206 further separates the feed into
an overflow stream including mostly water, some bitumen, and some
fine solids which is fed through the outlet 224 to the feed inlet
216 of the second hydrocyclone 204. The underflow stream produced
by the third hydrocyclone 206 at the outlet 226 forms a tailings
stream 234 for the system 200. The tailings stream 234 may be
further processed or diverted to a tailings pond for treatment. The
feedstock thus flows serially through the first, second, and third
hydrocyclones 202, 204, and 206, while the system process water
feed 208 flows through the third hydrocyclone, to the second
hydrocyclone, and through the pumpbox apparatus 100 to the first
hydrocyclone. The system process water 208 is thus generally
counter to the feedstock flow through the system 200, which serves
to improve recovery of bitumen from the feedstock.
[0068] The reservoir volume 102 of the pumpbox apparatus 100
provides a capacity for buffering the flow of feedstock to the
first hydrocyclone 202, thereby facilitating operation of the
hydrocyclones at a desired steady-state flow rate. In one
embodiment the cross sectional dimension of the reservoir volume
102 is about 7.3 meters by about 7.3 meters and the capacity of the
pumpbox is selected to accommodate flows of between about 1400
kg/m3 to about 1650 kg/m3 with a residence time of about 30 seconds
to about several minutes. For illustrative purposes, in one
arrangement, the retention time is about 1 minute. Advantageously,
the pumpbox apparatus 100 further facilitates collection of a
bitumen portion, in the form of aerated bitumen froth, that readily
floats to the surface of the accumulated liquid in the reservoir
volume 102. The first, second, and third hydrocyclones 202, 204,
and 206 thus operate on feed streams having bitumen requiring more
aggressive processing to separate low specific gravity bitumen from
the solids.
[0069] Advantageously, in the event of a failure of a pump, such as
the pump 160 shown in FIG. 2, the first liquid level in the
reservoir volume 102 of the pumpbox apparatus 100 will rise and
overflow at the inlet 112 of the collector 110, facilitating
diversion of the feedstock through the outlet 114 to a safe
location. Under these conditions solids will accumulate in the
reservoir volume, and the overflow at the inlet 112 will include
water, bitumen and some solids.
[0070] In other embodiments, the configuration of the system 200
may be changed to suit a particular feedstock. For example, where
it is desired to process a feedstock having a lower portion of
solids, the third hydrocyclone 206 may be omitted, in which case
the system process water may be provided to feed inlet 216 of the
second hydrocyclone 204, and the underflow 220 of the second
hydrocyclone forms the tailings stream for the system 200.
[0071] The pumpbox apparatus 100 may also be used in other
applications that generally require blending of two or more streams
having components of different specific gravity and where it is
desired to collect a low specific gravity portion that readily
floats upwardly within the accumulated liquid.
[0072] While specific embodiments of the invention have been
described and illustrated, such embodiments should be considered
illustrative of the invention only and not as limiting the
invention as construed in accordance with the accompanying
claims.
* * * * *